Front-to-back cooling system for modular systems with orthogonal midplane configuration

ABSTRACT

A front-to-back cooling system allows cooling of an apparatus containing two orthogonal sets of modules. Each set of modules is independently cooled. A vertical set of modules is cooled with vertical air flow across the modules that enters from a front of the apparatus and exhausts from a back of the apparatus. A horizontal set of modules is cooled with horizontal front-to-back air flow. When the horizontal set of modules is at the front of the apparatus, a plenum extending exterior to the vertical set of modules allows exhausting horizontally flowing air to the rear of the apparatus. When the horizontal set of modules is at the rear of the apparatus, a plenum extending exterior to the vertical set of modules allows moving air from the front of the apparatus to a chamber holding the horizontal modules.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. Ser. No. 12/167,604, filed onJul. 3, 2008, entitled “FRONT-TO-BACK COOLING SYSTEM FOR MODULAR SYSTEMSWITH ORTHOGONAL MIDPLANE CONFIGURATION”, by Gunes Aybay, et al.,currently pending [Attorney Docket No. 684735-1018].

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO A COMPACT DISK APPENDIX

Not applicable.

TECHNICAL FIELD

The present invention relates to the field of cooling systems, and inparticular to cooling of a modular system with orthogonal modules.

BACKGROUND ART

Systems that require very high bandwidth any-to-any connectivity among aset of modules typically use an orthogonal mid-plane configuration. Inthis configuration, a set of cards are plugged into the front side ofthe mid-plane in vertical configuration and another set of cards areplugged into the rear side of the mid-plane in horizontal configuration.This layout enables each front card to be directly connected to eachrear card, and makes it possible to eliminate the use of PCB signaltraces on the mid-plane to carry high speed signals.

However, the orthogonal configuration also creates a cooling challenge,especially in applications where front-to-back cooling is required.Vertical cards can be cooled using conventional cooling mechanisms withfront air intake and rear air exhaust, but cooling the horizontal cardswhile maintaining overall front-to-back air flow is challenging.

If front-to-back cooling is not required, the horizontal card cage canbe cooled using side-to-side air flow. However, many rack mountenvironments require front-to-back air cooling. One solution has been todivert air taken from a front intake to the back and run it up in acolumn next to the horizontal cards. Such a mechanism typically uses aset of fans or blowers to create the air pressure across the horizontalcards. However, the amount of air flow that is provided in such a systemis typically limited due the number of turns in the air path. Also, theplacement of one or two fan blades along the sides of the horizontalcards can severely limit the PCB area and panel surface that isavailable.

SUMMARY OF INVENTION

In one embodiment, a method of cooling an apparatus comprises: forming aplenum on a side of a first chamber of the apparatus, open to a front ofthe apparatus, partitioning the apparatus with an air-permeable barrier,forming a second chamber separated from the plenum and the first chamberby the air-permeable barrier, pulling air from the front of theapparatus via the plenum through the air-permeable barrier into thesecond chamber, and exhausting air from the second chamber to a rear ofthe apparatus.

In another embodiment, a method of cooling an apparatus comprises:cooling a first plurality of modules oriented in a first direction,comprising: pushing air from an edge of each of the first plurality ofmodules in the first direction, and pulling air from an opposite edge ofeach of the first plurality of modules in the first direction, andcooling a second plurality of modules oriented in a second direction,orthogonal to the first direction, comprising: moving air in the seconddirection across the second plurality of modules and through a plenumextending exterior to a first chamber containing the first plurality ofmodules, and exhausting air from the apparatus.

In yet another embodiment, a method of cooling an apparatus comprises:forming a plenum on a side of a first chamber containing a firstplurality of modules, moving air from a front of the apparatus throughthe plenum into a second chamber containing a second plurality ofmodules, the second plurality of modules mounted orthogonal to the firstplurality of modules, and exhausting air to a rear of the apparatus fromthe second chamber.

In yet another embodiment, a cooling system for an apparatus comprises:a first chamber, a plenum formed exterior to the first chamber andfluidly isolated from the first chamber, a second chamber in fluidcommunication with the plenum, a cooling system for the first chamber,comprising: a first fan, configured to push air across the firstchamber, and a second fan, configured to pull air from the firstchamber, and a cooling system for the second chamber, comprising: athird fan, configured to move air through the plenum into the secondchamber.

In yet another embodiment, a method of cooling an apparatus comprises:forming a first plenum on a side of a first chamber containing a firstplurality of modules, moving air from a front of the apparatus across asecond plurality of modules, the second plurality of modules mountedorthogonal to the first plurality of modules in a second chamber, andexhausting air from the second plurality of modules through the firstplenum to a rear of the apparatus.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate an implementation of apparatusand methods consistent with the present invention and, together with thedetailed description, serve to explain advantages and principlesconsistent with the invention. In the drawings,

FIG. 1 is a top perspective view illustrating an apparatus withorthogonal modules according to one embodiment;

FIG. 2 is a rear perspective view of the apparatus of FIG. 1;

FIG. 3 is a front perspective view of the apparatus of FIG. 1;

FIG. 4 is a side cutaway perspective view of the apparatus of FIG. 1;

FIG. 5 is a perspective view illustrating another embodiment of anapparatus with orthogonal modules;

FIGS. 6-7 are additional perspective vies of the apparatus of FIG. 5;

FIG. 8 is a front perspective view illustrating yet another embodimentof an apparatus with orthogonal modules;

FIG. 9 is a rear perspective view of the apparatus of FIG. 8;

FIG. 10 is a top perspective view of the apparatus of FIG. 8; and

FIG. 11 is a side cutaway perspective of the apparatus of FIG. 8.

DESCRIPTION OF EMBODIMENTS

FIG. 1 is a top perspective view illustrating an apparatus 100 withorthogonal modules according to one embodiment. The apparatus 100 canbe, for example, an enterprise class router, and the modules aretypically circuit boards. But the disclosed technique can be used in anyapparatus with orthogonal modules. In this embodiment, the apparatus 100contains a plurality of modules 110 oriented vertically in a frontsection of the apparatus 100 and a plurality of modules 130 oriented ina horizontal direction in a rear section of the apparatus 100. Modules110 and 130 are cross-connected through a mid-plane 120. In thisembodiment, the vertical modules 110 are enclosed by an enclosure 170 oneither side forming a plenum 150 on either side of the vertical modules110 extending from the front of the apparatus 100 past the mid-plane120. An air-permeable barrier 160 is placed between each of the modules130, forming a rear chamber of the apparatus 100. In some embodiments,barrier 160 is a perforated rippled material where the perforationpattern can be figured to create a pressure difference between the frontsection on one side of the barrier 160 and the rear section on the otherside of the barrier 160. This pressure difference can achieve a moreuniform air flow across more of the surface area of modules 130. Asshown in FIG. 1, fans or blowers 140 are placed at a rear portion of themodules 130. The fans or blowers 140 pull air from the front of theapparatus 100 through the plenum 150 and through the barrier 160 acrossthe modules 130 providing cooling to the modules 130. Heated air is thenexhausted through openings on the rear of the apparatus 100 as describedbelow. As shown in FIG. 1, in some embodiments, two blowers 140 arepositioned centrally at the rear of each module 130. In otherembodiments, a single fan or blower 140 could be used. Alternately, thefan or fans 140 could be positioned in other locations on the modules130 as desirable for uniform air flow across the surface of the modules130 or to provide higher air flow across portions of the surface area ofthe modules 130 that generate proportionally more heat than otherportions of the modules 130.

Turning to FIG. 2, a front view of the apparatus 100 shows the plenums150 on either side of the enclosure 170 surrounding the verticallyoriented modules 110. Additionally, FIG. 2 shows an independent coolingsystem for the modules 110. A plenum 240 is formed beneath thevertically oriented modules 110 and a lower fan tray 220 contains aplurality of fans that push air vertically across the surfaces of themodules 110 to provide cooling to the modules 110. An upper fan tray 230contains a plurality of fans that pull heated air from the modules 110and exhaust the heated air toward the rear of the apparatus 100 asdescribed below. A plurality of power supplies 210 are shown in FIG. 2at the bottom of the apparatus 100. In some embodiments, each of thesepower supply units provides its own front-to-back air cooling path fromfront openings or inlets in the power supply units 210.

Turning to FIG. 3, a rear view in perspective of the apparatus 100illustrates the outlets where heated air is exhausted to the rear of theapparatus 100. A collection of power supply exhaust outlets 310correspond to the power supply inlets 210 of FIG. 2. A pair of exhaustoutlets 330 is also shown for each of the modules 130, corresponding tothe two fans or blowers 140 illustrated in FIG. 1. Finally, outlets 320provide exhaust outlets for heated air that have cooled the verticalmodules 110 and is exhausted from the upper fan tray 230.

FIG. 4 illustrates the air flow path across the vertical modules 110. Asshown in FIG. 4, an upper plenum 410 is formed above the upper fan tray230 and the horizontally oriented modules 130 to provide an air path tothe exhaust ports 320 illustrated in FIG. 3.

In another embodiment, instead of pulling air from the front of theapparatus 100 across the horizontal modules 130, as illustrated in FIG.1, apparatus 500 pushes air across horizontal modules. One or moreblowers or fans 510 are positioned toward the front of the apparatus 500in a plenum 520. The fans 510 push air through the plenum 520 formedalong the side of vertical modules, not shown in FIG. 5 for clarity ofthe drawing. Putting the fans 510 in the plenum 520 can allow for betterfiltering and cleaner air throughout the air path across the rearhorizontally mounted modules than the negative pressure systemillustrated in FIGS. 1-4. In some embodiments, filters can be placed atthe inlets of the plenum 520 in front of the fans 510, but are not shownin FIG. 5 for clarity of the drawing. A barrier 530 is placed at theoutlets of the fans 510. As best shown in FIG. 7, openings 710 areformed in the barrier 530 to better control air flow through the plenum520. Air pushed through the plenum 520 is then pushed across thesurfaces of the horizontal outlets 540 and exhausted through the rear ofthe apparatus 500. As shown in FIGS. 5 and 6, the apparatus 500 has acooling system for the vertically oriented modules that is same asillustrated FIGS. 1-4. The only difference between the embodiments ofFIGS. 1-4 and FIGS. 5-7 is that instead of pulling the air through theplenum and across the cards as in FIGS. 1-4, the apparatus 500 pushesthe air from the front through the plenum 520 and across the cards 540.The numbered configuration and placement of fans shown in FIGS. 5-7 areexemplary and illustrative only and other numbers configuration andplacement of fans can be used.

In apparatus 100, as illustrated in FIGS. 1-4 (and similarly inapparatus 500, illustrated in FIGS. 5-7), the vertically orientedmodules 110 are in a front section of the apparatus 100 and horizontallymounted modules 130 are positioned in a rear section of the apparatus100. In other embodiments, vertically oriented modules can be placed inthe rear, and horizontally oriented modules can be placed in the frontof the apparatus. FIGS. 8-11 illustrate such an apparatus according toone embodiment.

Turning now to FIG. 8, a front perspective view illustrates an apparatus800 that contains front mounted horizontal modules 810. As withapparatus 100, power supplies 830 are cooled from air flow from thefront. Inlets 820 provide air to cool the rear mounted vertical modulesof the apparatus 800. Openings 840 in each of the horizontal modules 810provide an air path for cooling the horizontally mounted modules 810.

FIG. 9 is a rear perspective view of the apparatus 800 of FIG. 8.Vertically mounted modules 930 are cooled by an upper fan tray 920pulling air from inlets 820 of FIG. 8, then pushing that air downwardacross the surfaces of the vertically mounted modules 930. A lower fantray 910 contains exhaust fans that pull the heated air from thevertically oriented modules 930, exhausting the heated air throughplenums 960 formed below the lower fan tray to the rear of apparatus800. An end closure 940 holding the vertically oriented modules 930forms a plenum 950 on either side of the vertically oriented modules 930to exhaust heated air from the horizontally oriented modules 810.

Turning to FIG. 10, a top view shows the cooling path for the horizontalmodules 810. Cool air is pulled in through the openings 840 shown inFIG. 8, and pulled across the surface of the modules 810 to a radialblower 1020 mounted on either side of each of the modules 810. Theradial blowers 1020 then exhaust the heated air through the plenums 950to the rear of the apparatus 800. As in the apparatus 100 of FIG. 1, amid-plane 1010 connects the horizontally mounted modules 810 and thevertically mounted modules 930. Although described above as radialblowers, any desirable fan or blower can be used. The placement,configuration and number of blowers are exemplary and illustrative only,and other numbers configurations and placements can be used.

FIG. 11, a side view in perspective, shows the cooling path for thevertical rear modules 930 described above and the cooling path 1110 forpower supplies at the bottom of the apparatus 800. A plenum 1130provides air passage from the front of the apparatus 800 through inlets820 to the upper fan tray 920 which then pushes air vertically downwardacross the surfaces of the modules 930, where the lower fan tray 910exhausts the air through plenum 960 to the rear of the apparatus 800. Awall 1120 provides a portion of an enclosure above the horizontallymounted modules 810 to form the plenum 1130.

While certain exemplary embodiments have been described in details andshown in the accompanying drawings, it is to be understood that suchembodiments are merely illustrative of and not devised without departingfrom the basic scope thereof, which is determined by the claims thatfollow. By way of example and not limitation, the specific electricalcomponents utilized may be replaced by known equivalents or otherarrangements of components which function similarly and providesubstantially the same result.

1. A method of cooling an apparatus, comprising: forming a plenum on aside of a first chamber containing a first plurality of modules; movingair from a front of the apparatus through the plenum into a secondchamber containing a second plurality of modules, the second pluralityof modules mounted orthogonal to the first plurality of modules; andexhausting air to a rear of the apparatus from the second chamber. 2.The method of claim 1, moving air into the second chamber comprising:pushing air from the front of the apparatus through the plenum into thesecond chamber.
 3. The method of claim 1, moving air into the secondchamber comprising: positioning a fan on a rear portion of each of thesecond plurality of modules; and pulling air from the front of theapparatus through the plenum to the fan.
 4. The method of claim 1,moving air into the second chamber comprising: pulling air from thefront of the apparatus through the plenum across the second plurality ofmodules.